Method and apparatus for torpedo direction locating



Aug. 21, 1962 J. o. BAKER ETAL METHOD AND APPARATUS FOR TORPEDODIRECTION LOCATING 3 Sheets-Sheet 1 Filed Dec.

INVENTORS. J. 0. BAKER 3 ,N. N. ESTES A TTYS.

Aug. 21, 1962 J. o. BAKER ETAL METHOD AND APPARATUS FOR TORPEDODIRECTION LOCATING 3 Sheets-Sheet 2 Filed Dec. 8, 1950 Aug. 21, 1962 J.o. BAKER ETAL 3,050,707

METHOD AND APPARATUS FdR TORPEDO DIRECTION LOCATING Filed Dec. 8, 1950 3Sheets-Sheet 3 ullllllllllm m I RAM; ATTYS United States Patent "iceFiled Dec. 8, 1950, Ser. No. 199,908 1 Claim. (Cl. 340-6) (Granted underTitle 35, U.S. Code (1952), see. 266) This invention relates generallyto an improved acoustical method of torpedo or underwater objectivedirection finding and to an acoustical direction finder adapted forincorporation in the gun fire control ranging apparatus for shipboardanti-torpedo equipment. It is used in determining the presence of asound emitting objective moving under water in the vicinity of a vessel,locating the instantaneous position thereof with respect to the vesseland determining its path of tavel thereafter with respect to a givenshipboard reference axis, by continuous reception of the directionindicative emitted sounds and by viewing visual translated indicationsof the said sounds.

In prior methods and equipment for locating underwater objectivesvarious means have been used. Generally they are of a type embodying thetransmission of directed wave energy toward an objective and thereception by reflection of an echo impulse therefrom back to a receivingmeans incorporated in the direction finding apparatus. These systemsdepend for their proper functioning upon data derived fromtriangulations, one of which must include determination of a time cyclebetween the transmission of the directed wave energy which is directedto strike the object and the return to the source of any indicationavailable for use from that objective. This is a relatively slow speedsystem of directional scanning. Moreover it has been found that thesesystems will tend to indicate false targets such as whales and othermarine life. It is a further disadvantage of these systems that it israther difiicult to pick up a target as small as a torpedo at anyreasonable range. It is the intent of the present invention to overcomethese objections, and in so doing provide a ranging method which obviatmthe transmission of an energy impulse to be echoed back and which in sodoing eliminates the additional objection thereof of giving away onesown position through the transmission of such wave energy.

The torpedo direction locator of the instant invention is well adaptedforpickup of sound signals emitted by a signal source away from the shipsuch as that emitted by an underwater vehicle or torpedo moving in thevicinity thereof. The assembly is constructed to translate an impulsereceived at the ship into electrical energy capable of operation ofvisual display apparatus in the control room or control station onshipboard. It is arranged to translate the emitted signal from a sourceaway from the ship into visual-means-output indicative of theinstantaneous location, direction, path of travel, and rate of speed ofthe underwater missile with respect to the ships location andadditionally with respect to the ships path of travel; The device mayalso be adapted for providing indications as to the compass directionand bearing of the missile and to give course indicative informationwith respect to a compass data reference.

The sound reception device comprises a hydrophone located at a singlepoint or a plurality of points below the water line of the ship. Themicrophones thereof may be of a fixed or rotatable nature and mayprovide narrow beam or circular beam patterns depending on whether themicrophones are stationary or rotatable. Additionally, combinations ofnarrow beam and wide beam microphones may be employed in a singlemicrophone station unit. a

3,050,707 Patented Aug. 21, 1962 The signal pickup information of themicrophone is imparted through amplification apparatus to a visualindicator, as for example a cathode ray tube device or pointerindicating assembly and the direction of the source is correlatedtherewith through a suitable commutating system to produce directionindicative indications at the visual display station in correlation withthe direction of the sound picked up by the mcrophone.

In the case of the cathode ray tube visual indicating system a circularsweep pattern is imparted thereto in a manner whereby a pip is producedon the sweep thereof in response to a signal pulse, which is picked upby the microphone unit, amplified and applied to the deflection platesof the cathode ray tube.

One object of the present invention is the provision of an acousticaldirection finding system in which many of the foregoing disadvantagesare obviated and which is adapted to perform satisfactorily all theessential functions of the systems heretofore or now in general use andin which the time of accomplishment of locating and ranging anunderwater missile is materially reduced.

An additional object of the invention is the attainment of new andimproved locating and ranging of an underwater misile.

Another object of the invention lies in the accomplishment by improvedapparatus of underwater missile range and path of travel determinationsindividually or simultaneously from one or more of a plurality ofreceiving stations on shipboard.

Another object of the invention lies in the accomplishment by improvedapparatus, the detection, ranging and determination of path of travel ofa plurality of underwater missiles moving in the vicinity of a vessel.

An additional object of this invention resides in the use of a pluralityof receiving devices whereby the translated impulses of the severalreceiving means will be so correlated as to -provide a single visualindication of both range and bearing at the visual translation means.

An additional object of the invention resides in the provision of adevice for the reception of a plurality of sounds each from remotelylocated sources at a given instant and for a griven period of timethereafter and the translation of these several sound impulses at acommon visual indicating means whereby the information derived therefrommay be used in the aiming of guns for firing torpedo demolition charges.

An additional object of this invention resides in the use of a cathoderay tube as a visual indicating device for display of received soundsignals indicative of the location, range, path and rate of travel of anunderwater objective moving in the vicinity thereto, wherein the visualdisplay on the cathode ray tube is produced by a plural gun arrangementthereof embodied in a single envelope to provide indications on asuitably calibrated screen thereof.

An additional object of this invention resides in the provision of adevice for the reception at a given instant, and for a given period oftime thereafter of a plurality of missile indicative underwater soundseach from remotely located sources, and the subsequent translation ofthese several sound impulses for application at a cathode ray tubevisual indicating device of a type embodying a two gun display system,whereby underwater missile location, range, path and rate of travelinformation derived therefrom may be used in aiming the torpedodemolition guns of the ship firing system.

It is also an object of this invention to provide an improved method ofaiming the guns used in the firing of anti-torpedo charges bytranslating sounds resulting from the movement of the torpedo propellerthrough the water into useful impulses which control the plotting of theazimuthal bearing, instantaneous range, and path of travel of thetorpedo missile, or a plurality of missiles, and

the subsequent aiming of the anti-torpedo firing means.

Other objects and advantages of this invention will appear or be obviousfrom the hereinafter set forth description of the method of operation,combination of elements and arrangement and association of parts all aswill be best understood by reference to the following completedescription and accompanying drawings, wherein like reference charactersrefer to like or similar elements in the several drawings and in which:

FIG. 1 is a generally schematic diagram in elevation showing thelocation of the receiving and indicating apparatus on shipboard;

FIG. 2 is a diagram of one embodiment of the visual directionalindicating means of the invention incorporating a single rotatablecathode ray tube and a single rotatable pickup means;

FIG. 3 is a diagram of an embodiment similar to FIG. 2, using a fixedtube;

FIG. 4 is a diagrammatical illustration of a system in corporating aplurality of pickup circuits having their separate nodal imagesimpressed on a single visual indicator calibrated in terms indicative ofthe range of the objective;

FIG. 5 is a generally diagrammatical view in vertical section showingthe detailed arrangement of one form of a rotatable hydrophone componentfor use with the above embodiments of FIGS. 1 through 4 of the instantinvention.

Referring to FIG. 1 of the drawings for a generalized showing of theinvention, a vessel of any character is shown at 1. This vessel which isto be protected against underwater missiles is provided with a soundreceiving pickup device at 2, wherein the pattern of the microphoneunits of the pickup means are shown as narrow beam patterns. In FIG. 1the dash lines indicate the narrow beam microphone characteristic, itbeing understood that a single unit having a combination of narrow andwide beam microphones for sound pickup may be used. These sound pickupdevices are mounted on the ship at an underwater level and for purposesof illustration are shown on the keel thereof. The pickup devices aresuitably connected through amplifying assemblies shown in block form at3, to provide a raised power level signal, the output of which isapplied to the direction indicating apparatus shown in block form at 4.

The output of the amplifying unit may be applied to a cathode ray tube 5of the type shown in FIGS. 2 and 3, in a manner whereby a circular sweeppattern is applied to the trace thereof and further wherein a pip ornodal image will be produced on the circular sweep in a correlatedrelationship with the position of a sound emitted by a missile anddetected by the hydrophonic pickup 2. The thus produced nodal image isindicative of the direction of the sound source with respect to a givenaxis of the cathode ray tube. In the showing of FIG. 3 the referenceaxis of the cathode ray tube is On or parallel with the longitudinalaxis of the vessel.

The embodiment of FIG. 2 incorporates a gimbalmounted driven cathode raytube which is so coupled through the tube drive motor with a gyrocompass 10 as to be rotated in synchronism therewith. Target missileindications produced thereon are in correlation with the gyro compass 10and provide true bearing-information indications of the received sound.This embodiment using a rotatable cathode ray tube provides certainadvantages over the use of a fixed tube in which the reference axisthereof is correlated only with respect to the axis of a vessel. It isthus apparent that any change in the course. of the vessel will changethe position of thenode with respect to the reference axis. However,with the rotatable tube a change in the ships course will not registeras a change in the position of the nodal image as it will on thenon-rotatable tube arrangement, but will change only with missiletravel. The result is that with the use of a rotatable cathode ray tube,plotting is simplified. The only positional change in the nodal image inthe latter system is with a change in the path of travel of theobjective. In some cases wherein the objective is following a collisioncourse with the ship, indications on the rotatable tube may thus remainsubstantially fixed. The image will however show a generally uniformchange or deviation with changes in position of the missile in travelwhen the target missile is following a non-collision course with respectto the vessel. Such image change across the tube face providesinterpretable information indicative of the missiles by-passing thevessel. The rate of change of position of the missile indicative imageprovides rate of travel data on the target.

The underwater sound pickup device is shown in detail in FIG. 5.

The underwater sound pickup device is preferably enclosed within astreamlined casing 6 of Rho-C rubber or its equivalent and includes oneor a plurality of hydrophonic components 7 immersed in oil 8 such ascastor oil to effect transmission of the sound waves impressed by thewater upon the pickup casing 6, to the sound sensitive areas of thehydrophonic elements 7. This hydrophone assembly is shown for purposesof illustration but it is to be understood that the inventive concept isnot necessarily limited thereto since any suitable hydrophone may beused. In the assembled relationship thereof it includes a rotationimparting motor device at 9 to provide rotational drive therefor about anormally vertical axis or about such a substantially vertical axis asthat of the ship. The hydrophonic units of the pickup device areelectrically connected to an amplifier. The amplifier used therewith orone element thereof may if desired be mounted within the casing 6 andconnected by means of a slip ring assembly 11 to a cable 12 whichextends therefrom into the interior of the vessel and subsequently tothe direction indicating apparatus 4.

The direction indicating apparatus circuit between the pickup device 2and the cathode ray tube 5 is shown in FIG. 2 as including theamplifying apparatus 3, a rectifier 13 for the voltage output therefromand a continuously conducting cold cathode tube 14. The output of thistube is connected to a commutating device 16 of either the bar type, orthe resistance type such as the potentiometer shown for purposes ofillustration. The commutating device has the moving contact 21 thereofmechanically coupled through the shaft 17 of the pickup drive motor 9'to the rotatable hydrophone. The commutator is connected electrically atthe quadrant terminals thereof to the slip ring assembly 18 for thedeflector plate elements 19 of a driven cathode ray tube of theindicator assembly 4. The commutated output of tube 14 provides acircular sweep pattern for the cathode ray tube. The embodiment shown inFIG. 2 includes a tube driven by a conventional gyro compass 10, thedetails of which are not shown. The driving of the cathode ray tube incorrelation with, and by the compass serves to provide a bearing datacorrelation whereby the indication of a received sound will always begiven in terms of the true bearing of the sound source, irrespective ofthe direction of the ships course. In addition it indicates the trueangular relationship between the objectives course and a referenceindication corresponding to the ships course.

The cathode ray tube assembly is suitably supported on a system ofgimbal rings and bearings 20. The rotated hydrophone 2 of this systemmay be a single unit of the narrow beam type, and the use of such a unitwith a suitable commutation means 16 provides for the impression of asingle nodal image indicative of the bearing of the sound source on thesweep of the screen of the cathode ray tube as hereinafter described.The application of the commutating device 16 in this circuit is suchthat upon the tube 14 continuously conducting current to the severalresistance circuits of the said commutating means, and upon thecontinuous impression of voltages through the respective branches ofthese circuits to the slip ring structure and ultimately to the severalplates of the cathrode ray tube a circular sweep is produced on thescreen of the cathode ray tube. The impression of a voltage increase inresponse to a received sound signal through the movable contact 21 underrotation by the hydrophone drive motor 9 produces an outward radialdisplacement of a portion of the sweep on the cathode ray tube in theform of a pip or node. Observation of the position of the node and thetendency of the node to shift in position provides an indication of thecourse of travel of the objective missile, and in the case of theabsence of change in position the resulting interpretation of theindication is that of a collision course of the objective and vessel.

The system of FIG. 3 is similar to that of FIG. 2 with the exceptionthat the cathode ray tube is not rotatable and the indications on thetube are given with reference to a predetermined fixed axis of the tubeand hence of the vessel. This system shows the position of the receivedsound in terms of the true relationship thereof with the axis of theship, but does not give the true compass bear-.

ings of the sound source. In this embodiment the slip ring structure forthe tube is eliminated and the connections between the commutatingdevice 16 and the nonrotatable cathode ray tube are fixed.

For purposes of simplicity in illustration the apparatus arrangement ofFIG. 4 is shown as including a fixed or non-rotatable cathode ray tubealthough it is tobe understood that the plural feed-in circuit showntherein is equally well adaptable for use with a cathode ray tube of thetype shown and described above with reference to FIG. 2.

The apparatus and method of either FIG. 2 or FIG. 3

is further adaptable for use in determining the range of the receivedsound source as shown by the arrangement of FIG. 4 wherein a pluralityof multiple units combining highly directional and broad beam remotelylocated hydrophones 2 are rotated by their respective motors 9 throughtheir shafts 17 so as to sweep through 360 at a convenient rate as forexample ten revolutions per second. The rotating contact 21 of thecommutating device 16 which is mechanically coupled to the shaft 17, isin its respective electrical circuit of the deflector plates 19 of thedual cathode ray tube 5. With a fixed bias applied to the deflectorplates, the beam spot of the cathode ray tube traces a pair of circleson the screen 5a thereof. In the event the hydrophones sweep a soundsource such as an approaching torpedo, the outputs of their respectiveamplifiers 3 are fed into the respective bias of the corresponding setof deflector plates to add a bump or node on the circular trace or sweepof the tube screen. The voltage added by' the amplifier and impressedupon the respective deflector plate bias circuit is made sufiicientlyhigh to cause the pip or node to appear as along narrow line. Theintersection of the two lines then provides a point on the screenscalibrated scale indicating the position of the sound source and'theindicated distance from the tube center to the above mentioned pointprovides an indication of the instantaneous range of the sound source.Continued observation of the point of intersection of the two traces onthe screen provides an indication of the path of travel of theobjective.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claim the invention maybe practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or forthe Govermnent of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

Apparatus for use aboard a ship for detecting, ranging and determiningthe azimuth of an underwater missile emitting characteristic sounds asit moves through the water, comprising in combination; a plurality ofrotatable, directionally responsive, hydrophones in the aft portion ofsaid ship; motor means connected to said hydrophones to provide rotationthereof; a dual beam cathode ray oscilloscope having first and secondsets of deflection plates and a reference axis fixed with respect to thelongitudinal axis of said ship, first means connected between saidhydrophones and said first set of deflection plates and driven by saidmotor means to provide a generally circular display centered on saidreference axis, and to produce an elongated pip on said circular displaywhen said hydrophones detect said missile, the position of said pip withrespect to the center of said circular display being correlative to thebearing of the missile with respect to said hydrophones; said firstmeans including a rectifier, a potentiometer driven by said motor meansfor synchronous rotation with said hydrophones and being connectedbetween said rectifier and said first set of deflection plates, andmeans connected between said hydrophones and said rectifier foramplifying the signal produced by said hydrophones; a second pluralityof rotatable, directionally responsive hydrophones in the bow portion ofsaid ship; second motor means connected to said second hydrophones toprovide rotation thereof; second means connected between said secondhydrophones and said second set of deflection plates and driven by saidsecond motor means to provide a second generally circular display on theface of said oscilloscope displaced from said first display and centeredon said reference axis and to produce a second elongated pip on saidsecond circular display when said second hydrophones detect saidmissile, the position of said second pip with respect to the center ofsaid second circular display being correlative to the bearing of themissile with respect to saidsecond hydrophones; said second meansincluding .a second rectifier, a second potentiometer driven by saidsecond motor means for synchronous rotation with said second hydrophonesand being connected between said second rectifier and said second set ofdeflection plates, and means connected between said second hydrophonesand said second rectifier for amplifying the signal produced by saidsecond hydrophones; and range indicating indicia formed on the face ofsaid cathode ray oscilloscope whereby the range indicia at theintersection of said first and said second pips indicates the range tosaid underwater missile.

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